Phototherapy is used for various purposes such as treatments for diseases such as neonatal jaundice, psoriasis, and acne, pain palliation, and beauty treatments. Green light and blue-white light are used for treatments for neonatal jaundice, ultra-violet light is used for treatments for psoriasis, and blue light, red light, and yellow light are used for treatments for acne. In such a manner, various kinds of light sources are used in accordance with uses.
NPL 1 describes a treatment method for skin ulcer infected with methicillin-resistant Staphylococcus aureus (hereinafter referred to as “MRSA”), which uses near ultra-violet light. This treatment method is a therapeutic method in which an infected part with antibiotic resistant Staphylococcus aureus is irradiated with near ultra-violet light (at a wavelength of approximately 410 nm) and the bacteria are thereby killed and is based on a process in which systemically administered 5-aminolevulinic acid (hereinafter referred to as “ALA”) is metabolized to protoporphyrin IX (hereinafter referred to as “PpIX”) and accumulated in the bacteria and the bacteria are destroyed from internal portions of cells or the bacteria by active oxygen which is generated when PpIX is decomposed by near ultra-violet light.
The above treatment method has been considered as a very highly promising technique with a wide application range, which causes no side effect for cells themselves of the affected part but kills antibiotic resistant bacteria without causing antibiotic contamination.
For popularization of such a technique, a light irradiation device is demanded which may perform uniform light irradiation for affected parts with various three-dimensional shapes and sizes.
In related art, as a light irradiation device, for example, devices that use light sources such as an excimer lamp and an arc light, devices that use laser as light sources, devices of a type that performs planar irradiation with treatment light by using optical fibers, and so forth have been known.
However, the above-described related art has the following problems.
For example, in a case of the light sources such as the excimer lamp and the arc light, the affected part is arranged in a specific distance with respect to a fixed light source and is irradiated with the treatment light. However, in a case of using such a lamp type light source, the treatment light fails on other portions than the affected part because the irradiation area is too large. Thus, there is a concern about various side effects for a normal site. Accordingly, some sort of shielding measure for preventing irradiation for the normal site with the treatment light is requested, and a treatment consumes time and labor. For example, in a case where a disease that occurs to a portion of a face, an eye pad (blindfold) for protecting eyes that are normal sites is requested. In addition, in order to protect the normal sites of the face, a mask that only exposes the affected part of the face is also requested. Further, a patient has to keep a still posture for several ten minutes in a state where his/her body is restrained for the treatment. This is not a comfortable experience although the experience is for the treatment. Further, for example, in a case where the affected part has a curved surface as on an arm or a leg, a lamp type irradiation device may force the patient to keep a very difficult posture depending on a site such as a front side, a back side, or a lateral side. Further, the irradiation intensity is different with respect to each position of the affected part in accordance with an angle or a distance between the affected part that has a curved portion and the lamp. Thus, a case may occur where it is difficult to uniformly irradiate the whole affected part with the treatment light. In addition, because a device that uses such a lamp type light source has many accessory devices such as a power source and a cooling device and is large in size, the device requests a large space for installation and is expensive in price. Accordingly, the device may be installed only in a treatment facility, and attendance at the treatment facility is necessary.
Meanwhile, in the device that uses laser as the light source, because the irradiation light is spot light with a small irradiation area, scanning by the spot light is requested so that the whole affected part with a large area is irradiated with the treatment light, and the device becomes complicated and expensive.
Further, because the efficiency of delivering light into the optical fibers is comparatively low, a device of a type that performs planar irradiation with the treatment light by using the optical fibers necessarily has low irradiation power and only fits the treatment for a comparatively long time.
Based on such a background, a flexible substrate is demanded which includes the light source capable of keeping a specific distance from the affected part and of covering the affected part along the shape of the affected part.
For such a desire, several techniques that will be described in the following have been suggested.
For example, PTL 1 discloses a light irradiation device in which laser and light-emitting diodes (LED) as light-emitting light sources are arranged on the flexible substrate and which is used while being wound around the affected part. PTL 2 discloses a light irradiation device for a face in which the LEDs as the light emitting light sources are arranged on the flexible substrate and which is used by covering the face. PTL 3 discloses a light irradiation device with flexibility in which a large number of LEDs serving as the light-emitting light sources are arranged on the flexible substrate and which performs light irradiation by winding the flexible substrate around the affected part. PTL 4 discloses a light irradiation device in which the LEDs serving as the light-emitting light sources are arranged inside a cap on an assumption of application to a head. PTL 5 discloses a light irradiation device in which the LEDs serving as the light-emitting light sources are arranged on the flexible substrate, a light-transmissive substance is interposed between the affected part and the LEDs, and light emitted by the LEDs may thereby be transmitted to the affected part.
Based on PTLs 1 to 5, a flexible base material with flexibility covers the affected part, and the affected part may thereby be covered along the shape of the affected part. Further, the LED is small compared to other light sources and may perform light irradiation for the affected part with a curved surface. In a case where size reduction and weight saving of the light irradiation device are made, it is possible to perform the treatment home. Thus, it is expected that the flexible base material that includes the LEDs covers the affected part and performs light irradiation as described in PTLs 1 to 5, various loads on patients may thereby be alleviated, and the affected part with a curved surface may be irradiated with uniform treatment light.